Question

A 120V Microwave uses 8A of current. It runs for 15 hours over the course of a month. If electrical energy costs $0. 11/KWh, what does it cost to run the microwave for the month

Answer 1

1 kw-hr = 1000 w * 3600 sec = 3.6E6 Joules

E = P t = 120 J/C * 8 C/sec * 3600 sec /hr * 15 hr = 5.18E7Joules

where E is energy used by microwave

5.18E7 / 3.6E6 * .11 = $1.58 cost to run for 15 hrs